1. Field of the Invention
The present invention relates to an optical device having the capability to optically correct image blur in a sensed image due to camera shake and the like.
2. Description of the Related Art
Optical devices and image sensing devices including video cameras are designed to be able to easily take good photographs by mounting an anti-vibration function on the optical devices. Such an anti-vibration function detects shaking of the optical device as angular velocity using, for example, an angular velocity sensor, determines a shake amount from the detected angular velocity, shifts an optical path of incident light by driving a correction optical system based on the determined shake amount, and thereby stabilizes an image.
However, there are limits to the range in which the correction optical system can be driven within an optical system. When the limits of the drivable range (control limit positions) are exceeded, it becomes impossible to correct the shaking of the device appropriately.
To solve this problem, Japanese Patent Laid-Open No. 4-328533 proposes to return the correction optical system to the center of the drivable range (center of a movable range) when the correction optical system reaches a limit of the movable range.
Also, Japanese Patent Laid-Open No. 09-080556 proposes a method for correcting a driving amount of the correction optical system so as to return the correction optical system to the center of its movable range when the correction optical system approaches a limit of the movable range, where the driving amount is calculated using a centering gain.
However, with the method proposed in Japanese Patent Laid-Open No. 4-328533, when panning or tilting (hereinafter referred to as “panning” regardless of the direction of panning or tilting) is done for an extended period of time, the correction optical system remains at a limit of the movable range. Consequently, when the correction optical system reaches the limit of the movable range, the shaking of the device cannot be corrected appropriately during panning.
Also, with the method proposed in Japanese Patent Laid-Open No. 09-080556, if a panning operation is continued even after the correction optical system is driven toward the center of the movable range based on the centering gain, the correction optical system reaches the limit of the movable range again as described above. Consequently, the correction optical system repeats the cycle of being driven in a direction of a control limit position due to changes in angular displacement data due to panning and being driven to the center of the movable range due to a centering process, causing blur or unnatural angle-of-view changes in the sensed image.